Electric fuse of the cartridge type



Aug. 17, 1937. OR 2,090,220

ELECTRIC FUSE OF THE CARTRIDGE TYPE Filed Jan. 15, 1937 //v1//v 70/?RNEST MOOR ZAAMM ATTORNEYS Patented Aug. 17, 1937 ELECTRIC FUSE OF THECARTRIDGE TYPE Ernest Moor, Gravesend, England, assignor to W. T.Henleys Telegraph Works Company Limited, London, England, a Britishcompany Application January 15, 1937, Serial No. 120,743 In GreatBritain January 25, 1936 1 Claim.

This invention relates to electric fuses and cutouts of the cartridgetype. In fuses of this type the fusible element is disposed in a tubularmember and its ends are connected to terminal caps 5 mounted on the endsof the tubular member. In cases where the tubular member or barrel, asit is frequently termed, is of a material such as porcelain that cannotbe machined or drilled there arises a difiiculty in securing the closuremember in a satisfactory manner. Hitherto the closure member or cap hasgenerally been made in the form of a flanged lid which has been securedto the end of the barrel by making a cement joint between the flange andthe peripheral surface of the barrel. This is unsatisfactory in that thecement is liable to disintegrate with the result that the whole fuse mayfall to pieces when being handled or after it has been in service forsome time.

By the present invention we provide a cartridge fuse which is free fromthe objectionable faults possessed by the type in which the cap iscemented to the barrel.

In the improved construction of cartridge fuse 5 there is fitted on eachend of the barrel which houses the fuse element or elements, anapertured metal inner cap and a metal outer cap between which is locatedthe bent over end of the fuse element. The inner cap fits over the endof the barrel and is retained in position by spinning or pressing theedge of its circumferential flange into a circumferential groove in thebarrel. The outer cap fits over the inner cap and is retained inposition thereon by soldering to the inner cap.

With this arrangement the inner cap is secured to the barrel in aninexpensive, reliable and permanent manner and the end of the elementcan be held in good contact with the inner face of the outer or with theouter face of the inner cap or with both these faces. By making theouter cap a push fit on the inner cap it can readily be detached, forthe purpose of inserting new elements into the cartridge, by melting thesoldered joint.

In order that the invention may be more fully understood an example of aheavy duty cartridge fuse constructed in accordance with the inventionwill now be described with reference to the r accompanying drawingwherein,

Figure 1 is a sectional elevation of one half of the fuse, and

Figure 2 is an end elevation of the fuse.

The barrel portion of the fuse shown in the drawing comprises a shortcylindrical body I of porcelain having one or more longitudinal channels2 which extend therethrough and are disposed symmetrically about theaxis of the barrel. At each end the external diameter of the barrel isreduced, as shown at 3, and a peripheral groove 4 is provided at thepoint where the change in external diameter occurs. This groove isroughly of V-shape with the base of the V and the corners at theextremities of the V rounded off, particularly on the side of the groovenearer to the end of the barrel. On the reduced end portion of thebarrel is fitted a thin inner cap preferably of copper. This consists ofa circular disc suitably apertured to correspond with the channels inthe barrel and having a peripheral flange G of which the internaldiameter corresponds to the external diameter of the reduced portion ofthe barrel. The depth of the flange is such that its edge 1 extendsapproximately to the centre of the circumferential groove. The edge l isthen spun or pressed into the groove 4. The pressure may be applieduniformly around the whole periphery of the flange or at multiplicity ofpoints around the periphery. Preferably a gasket 8 of asbestos or othersuitable arc resisting, cushioning material is inserted between the faceof the cap 5 and the end of the barrel I. In each passage 2 is disposeda pair of fuse elements 9. The central parts of these elements 9 arebunched together and located in the centre of the passage but the stemsdiverge from one another so that near the end of the passage they lie onopposite sides thereof. The extremities of the stems pass through theapertures in the cap and are bent over as shown at It] and pressed intoengagement with the outer face of the cap 5. They may, if desired, besoldered as shown at H or welded to the cap or they may be soldered andwelded to the cap. The ends of the channels are then closed by plugs l2of asbestos or the like. Over the inner cap 5 is an outer cap [3 whichis of heavier gauge metal, preferably copper or brass, and consists of acircular disc having a circumferential flange 2| of which the internaldiameter corresponds to the external diameter of the flange 5 of theinner cap. The outer cap [3 carries contact blades I4, each of which isformed with a base portion l5 which is riveted or welded, as shown atH5, or soldered, as shown at l8, to the outer face of the cap or thebase portion may be riveted or welded, as shown at 16, and soldered, asshown at Hi, to the outer face of the cap. The outer cap is pressed onthe inner cap 5 so as to clamp the ends ID of the fusible elementsbetween the two caps and is retained in position by soldering the edgeof the flange 2! to the flange 6, as shown at H). Preferably an asbestosgasket 20 is in serted between the bent over ends ll] of the elementsand the inner face of the outer cap. It will be appreciated that theoperation of spinning or pressing the edge of the inner cap into thegroove on the barrel presents no difficulty and does not involve the useof special chucks or other supporting devices because the operation iscarried out before the two outer caps carrying the contact blades arefitted.

What I claim as my invention and desire to secure by Letters Patent is:-

A cartridge fuse comprising at least one fuse element, a tubular membersurrounding said element and having a pair of circumferential grooves inits peripheral surface, and, mounted on each end of said member, anapertured inner metal cap and an outer metal cap, between which islocated a bent over end of said fuse element, said inner cap having acircumferential flange and fitting over the end of said member and beingretained in position by the engagement of at least part of the edge ofits flange in the adjacent.

circumferential groove in said member and said outer cap fitting on saidinner cap and being retained in position thereon by soldering to saidinner cap.

ERNEST MOOR.

